Exhibit 10.21

                   SIXTH AMENDMENT TO SECURED CREDIT AGREEMENT
                       AND SECURED REVOLVING CREDIT NOTES


Harris Trust and Savings bank
Chicago, Illinois

Mercantile bank of St. Louis
   National Association
St. Louis, Missouri

Gentlemen:

         The undersigned, Maverick Tube Corporation, a Delaware corporation (the
"Borrower")  refers to the Secured Credit Agreement dated as of May 15, 1992, as
amended (the  "Agreement")  and currently in effect  between the Company and you
(the  "Banks")  and Harris Trust and Savings  Bank,  as agent for the Banks (the
"Agent").  All capitalized  terms used herein without  definition shall have the
same meanings as they have in the Agreement.

         The  Borrower  hereby  applies  to the Agent and the banks for  certain
modifications to the Agreement and the Borrower's  borrowing  arrangements  with
the Agent and the Banks.

1.       AMENDMENT

         Upon your  acceptance  hereof in the space  provided  for that  purpose
below, the Agreement shall be and hereby is amended as follows:

         (a)  Effective  6/30/96,  Section 7.8  subsection  (a) of the Agreement
shall be and hereby is amended by deleting  the ratio "1.80 to 1"  appearing  in
the last line of the first paragraph of said Section and  substituting  therefor
the ratio "1.50 to 1".

         (b)  Section  1.1(a)  of the  Agreement,  the  last  line of the  first
paragraph, shall be amended and as so amended shall read as follows:

         "...date hereof to and including May 31, 1998 (the "Termination Date").

         (c) The Secured  Revolving  Credit Note of the Borrower to Harris Trust
and Savings Bank,  dated May 15, 1992,  is hereby  amended by replacing the date
"May 31, 1997" appearing in the first  paragraph  thereof with the date "May 31,
1998."

         (d) The Secured  Revolving  Credit Note of the  Borrower to  Mercantile
Bank of St. Louis National Association, dated May 15, 1992, is hereby amended by
replacing the date "May 31, 1997" appearing in the first paragraph  thereof with
the date "May 31, 1998."

2.       CONDITIONS PRECEDENT

         The   effectiveness   of  this  Sixth   Amendment  is  subject  to  the
satisfaction of all of the following conditions precedent:

         (a) The Borrower and the Banks shall have executed this Sixth Amend-
ment.

         (b) The Banks shall have received  copies executed or certified (as may
be appropriate)  of all legal documents or proceedings  taken in connection with
the  execution  and  delivery  hereof and the other  instruments  and  documents
contemplated hereby.

         (c) All legal matters incident to the execution and delivery hereof and
of the  instruments and documents  contemplated  hereby shall be satisfactory to
the Banks and their counsel.

3.       REPRESENTATIONS

         In order to  induce  the  Banks  to  execute  and  deliver  this  Sixth
Amendment,  the  Borrower  hereby  represents  to the Banks  that as of the date
hereof and as of the time that this Sixth Amendment becomes  effective,  each of
the  representations and warranties set forth in Section 5 of this Agreement are
and  shall be and  remain  true and  correct  (except  that the  representations
contained in Section Sixth shall be deemed to refer to the most recent financial
statements  of the Borrower  delivered to the Banks) and the Borrower is in full
compliance  with all of the terms and conditions of the Agreement and no Default
as defined  in the  Agreement  as amended  hereby nor any Event of Default as so
defined,  shall have  occurred  and be  continuing  or shall arise after  giving
effect to this Sixth Amendment.

4.       MISCELLANEOUS

         (a) Collateral  Security  Unimpaired.  The Borrower  hereby agrees that
notwithstanding  the execution and delivery hereof, the Security Documents shall
be and remain in full force and effect and that any rights and  remedies  of the
Banks  thereunder,  obligations  of the  Borrower  thereunder  and any  liens or
security  interests  created or provided for  thereunder  shall be and remain in
full force and effect and shall not be affected,  impaired or discharged hereby.
Nothing  herein  contained  shall in any manner affect or impair the priority of
the liens and security  interest created and provided for by Security  Documents
as to the  indebtedness  which would be secured  thereby  prior to giving effect
hereto.

         (b) Effect of Amendment.  Except as  specifically  amended and modified
hereby,  the  Agreement  shall stand and remain  unchanged and in full force and
effect  in  accordance  with its  original  terms.  Reference  to this  specific
Amendment  need not be made in any note,  instrument  or other  document  making
reference to the Agreement,  and reference to the Agreement in any of such to be
deemed to be a reference to the Agreement as amended hereby.

         (c) Costs  and  Expenses.  The  Borrower  agrees  to pay on demand  all
out-of-pocket  costs and expenses  incurred by the Banks in connection  with the
negotiation, preparation, execution and delivery of this Sixth Amendment and the
documents and transactions  contemplated hereby, including the fees and expenses
of counsel to the Banks with respect to the foregoing.

         (d)  Counterparts;  Governing Law. This Sixth Amendment may be executed
in any  number of  counterparts  and by  different  parties  hereto an  separate
counterparts,  each of which when so executed  shall be an  original  but all of
which to constitute one and the same agreement. This Amendment shall be governed
by the internal laws of the State of Illinois.

Dated October 16, 1996.

                                                   MAVERICK TUBE CORPORATION

                                                   By: /s/ Charles Struckhoff

                                                   Its:  Chief Financial Officer

         Accepted  and agreed to at Chicago,  Illinois,  as of the date and year
last above written.

                                                   HARRIS TRUST AND SAVINGS BANK

                                                   By: /s/ Bonnie A. Polic

                                                   Its: Vice President


                                                   MERCANTILE BANK OF ST. LOUIS
                                                      NATIONAL ASSOCIATION

                                                   By: /s/ David Higbee

                                                   Its: Vice President